All Z measurements are from Z zero (Top of Material). Since that changes as the material wraps and moves from cutting, you have to reestablish Z zero often while cutting (before a pierce move) THC Corrections just prevents the Z from moving past preset limits. Min should be the lowest you will let the Z go while cutting. If you touch-off and reference on a high spot then proceed to cut to a lower spot and you have the MIN set to .2 then it won't follow the material down. The MIN should be 0 or perhaps even slightly negative. I set mine to -.125 for most cutting. It's just a failsafe so if you were to plunge off the side of the material, the Z would drive down as far as Z would go and possibly hit a grid bar and snap off the end of the torch. It's less concern on THC's that have the Dynamic anti-dive like the MP3000-DTHC and as I understand, the THC301D. The anti-dive would sense the voltage spike from the open cut and lock Down Movement. We have that as one of the CUT PROFILE parameters as a percentage of preset volts and is adjustable by the user. We found the number needs to change for thicker material.
Totally Modular CNC Electronics.